One conventional connector of the type described above which has widely been used in the art is illustrated in FIGS. 5(a) through 5(c) of the accompanying drawings. The conventional connector will be described below with reference to FIGS. 5(a) through 5(c). The conventional connector comprises a socket 1 shown in FIG. 5(a) and a plug 2 shown in FIG. 5(b). When the socket 1 and the plug 2 are connected to each other, they are combined with each other in a state shown in FIG. 5(c).
The socket 1 comprises a first body 1A which is made of plastics and has a cylindrical shape, a plurality of pin holes 1B extending through the first body 1A, a plurality of sheath-shaped connection terminals 1C covering the respective inner circumferential surfaces of the pin holes 1B, and a tubular socket member 1D housing the first body 1A therein. The connection terminals 1C are connected by respective lug terminals, not shown, to a cable 3 which is connected to an electric device. The plug 2 comprises a second body, not shown, which is made of plastics and has a cylindrical shape, a plurality of pins 2B extending through the second body and insertable respectively into the pin holes 1B, and a tubular plug member 2C housing the second body therein. The socket member 1D has a connecting end whose outside diameter slightly smaller than the inside diameter of a connecting end of the plug member 2C. When the socket member 1D is fitted in the plug member 2C, the socket 1 and the plug 2 are electrically connected to each other. Although not shown, the socket member 1D has a connecting portion with an axial key disposed on the outer circumferential surface thereof, and the plug member 2C has a connecting portion with a slot defined in the inner circumferential surface thereof in alignment with the key. When the socket 1 and the plug 2 are to be connected to each other, they are positioned with respect to each other by the key and the slot.
The connector has a lock mechanism 4 shown in FIGS. 5(a) through 5(c). As shown in FIGS. 5(a) through 5(c), the lock mechanism 4 comprises a pushbutton 4A mounted on a surface of the end of the socket member 1D and extending axially, a ridge 4B disposed on a surface of the pushbutton 4A extending toward the connecting end and integrally formed with the pushbutton 4A, a leaf spring 4C for resiliently biasing the pushbutton 4A, and an engagement groove 4D defined in the inner circumferential surface of the plug member 2C near the connecting end thereof.
For connecting the socket 1 and the plug 2 to each other, the key of the socket member 10 and the slot of the plug member 2C are aligned with each other, and then the connecting portion of the socket member 1D is inserted into the connecting portion of the plug member 2C. When the connecting portion of the socket member 1D is inserted into the connecting portion of the plug member 2C, the ridge 4B of the lock mechanism 4 is pushed radially inwardly against the resilient force of the leaf spring 4C. When the connecting portion of the socket member 1D reaches the end of its inserting stroke, the ridge 4B is fitted into the engagement groove 4D in the inner circumferential surface of the plug member 2C under the bias of the leaf spring 4C, as shown in FIG. 5(c), thereby locking the socket 1 and the plug 2 in a connected state. The socket 1 is now locked against removal from the plug 2. For disconnecting the socket 1 from the plug 2, the pushbutton 4A of the socket member 10 is pushed to displace the ridge 4B out of the engagement groove 4D. The socket 1 is then removed and hence disconnected from the plug 2.